Observed and simulated upper-tropospheric water vapor feedback

Results are compared to simulations from a general circulation model, the NCAR Community Atmosphere Model (CAM), to see if the model can reproduce the variations.

Results indicate that the upper troposphere maintains nearly constant relative humidity for observed perturbations to ocean surface temperatures over the observed period, with increases in temperature _1.5 times the changes at the surface, and corresponding increases in water vapor (specific humidity) of 10%–25% °C_1. Increases in water vapor are largest at pressures below 400 hPa, but they have a double peak structure.